Hi all, I purchased second hand UK rebranded Chinese CNC machine with 8 x 4 ft bed. It has the generic Rich Auto controller. I did a flawless 2.5 hour cut yesterday with over 30 pieces - I am impressed by the accuracy of the machine. This morning I turned on my machine and when homing the axis. Z decided to travel down rather than up - I had to hit the emergency. I'm glad I was paying attention ha. After turning the machine on again, I skipped homing. When I pressed Z+, the head moved down. Then I pressed Z- which operated correction. I hit Z+ again and it started working correctly,. I then homed and it did indeed travel up towards the limit switch. After, I began to process a file and even though on Vcarve my depth of cut was that of the thickness of the material, it was leaving slightly more than an 'eggshell' layer at the bottom. I cancelled the file and checked the Z zero - this was not consistent with what I set it to. it was 2mm higher. I then homed Z. I when I went to Z 0, it was correct. I checked the collet and it was tight. I checked the motor shaft coupled grub bolts and there was tight. There was no play or backlash. There only difference between yesterday and today was the program. Yesterday I was cutting 18mm hardwood ply in 6 passes. Today I tried 5 passes with a 4mm compression bit. This seems to be a very powerful machine. Surely I can power through - unless that chips are being compacted into the cut?? I changed back to cutting in 6 passes and it was flawless thankfully. With the issues outline above - I have ruled common mechanical issues. Could it be electrical (EMI, loose wire) - I have to investigated this yet. Thank you. Ats.
I am not familiar with your controller, but the symptoms suggest two possibilities - first, one loose connection to your Z stepper motor. Second, not homing as soon as you switch on - this sets a reference point (the back, right, up corner as the maximum dimension for each axis) for all future moves. Alex.
